Claims:WE CLAIM:
1. A ringed cooling fan (5) for a vehicle engine with reduced noise and improved heat dissipation, comprising:
a circular hub portion (2);
a plurality of fan blades (8);
a circumferential ring (10) positioned on the periphery of the said fan blades;
characterized in that the fan blades (8) are equidistantly placed, have a leading edge (09) and trailing edge (20), wherein the trailing edge is in contact with the hub (2), the blade has a convex surface (11) and a concave surface (12), the fan is configured to rotate in clockwise direction wherein the fan blades are sweep forward curved blades, and on rotation of the fan the convex portion (11) of the said fan blade in the upstream of the airflow and a concave portion (13) in the downstream of the air flow, the and
wherein the eddies at the edges of blades makes air flow uniform resulting in reduced noise and improved heat dissipation, and the ring (10) around the aerofoil, the air vortices formed by flow separation around the fan periphery are being broken upon contact with the ring (10).

2. The cooling fan for vehicle engine of tractors as claimed in claim 1, wherein the said cooling fan (5) has at least 7 fan blades (8).

3. The cooling fan for the for vehicle engine of tractors as claimed in claim 1,wherein the said cooling fan (5) has a diameter of 390-400mm

4. The cooling fan (5) for vehicle engine of tractors as claimed in claim 1 wherein the said fan hub (2) has a diameter of fan (5) is 394mm and diameter of hub (2) is 118nm.

5. The cooling fan (5) for vehicle engine of tractors as claimed in claim 1 wherein the camber angle of the aerofoil (30) is in the range of 3-18 degrees.
6. The cooling fan (5) for vehicle engine of tractors as claimed in claim 1, wherein the direction of the airflow is from the convex to the concave portion.

7. The cooling fan (5) for vehicle engine of tractors as claimed in claim 1 wherein the thickness ratio t/c is in the range of 3-7.

8. The cooling fan (5) for vehicle engine of tractors as claimed in claim 1 wherein stagger angle is in the range of 45-62 degrees.

9. The cooling fan for the for vehicle engine of tractors as claimed in claim 1,wherein the pressure drop across the inlet/outlet of the fan draws fresh air thereby increasing the airflow

Dated this day 4th of April 2022

, Description:RINGED COOLING FAN FOR AGRICULTURAL TRACTORS
FIELD OF INVENTION
The present invention relates to a cooling fan for vehicles. Particularly a cooling fan in the automotive field, e.g., for a motor vehicle. In particular, the present invention relates to a fan structure with a ring on periphery for cooling system on Agricultural tractor enabling the reduction of aero dynamic fan noise by minimizing turbulence.
BACKGROUND OF INVENTION

Generally cooling systems are used in tractors that dissipates heat from the surface of the engine. Radiators are usually located in front of the tractor to get the most out of the air flow to help keep the coolant temperatures down. Air blower or cooler fans circulates air to control the temperature in the engine, especially from the cylinder to maintain optimum temperature of engine for efficient operation. Usually cooling fan in a vehicle engine is placed in a semicircular ducting where the ducting covers the cylinder head such that its interior is fitted with baffles which direct the flow of air over the engine cooling fins and through an oil cooler. In conventional systems the cooler fans involves blades or fins that are radially arranged which upon rotation facilities the cooling . High traction vehicles such as tractors will generate more heat where there is a chance that most of the fuel energy being wasted as exhaust gas. Conventional cooler fans generates noise which in turn has a negative impact on the efficiency of the engine. Many improved versions of cooler fans are available currently.
EP0945627 discloses a axial flow fan comprising a central hub, a plurality of blades in which each blade having a root and an end and being delimited also by a convex edge, whose projection onto the plane of rotation of the fan is defined by a parabolic segment, and by a concave edge whose projection onto the plane of rotation of the fan is defined by a circular arc. The blades consist of sections having aerodynamic profiles with a face comprising at least one initial straight-line segment and a blade angle that decreases gradually and constantly from the root towards the end of the blade according to a cubic law of variation as a function of the fan radius.
US5961289A discloses an axial fan for a cooling blower of a vehicle engine has fins with leading and trailing edges, and aero acoustic optimization is provided by each of the leading edges and trailing edges having a strong forward sweep followed by a strong backward sweep in the manner of a bird's wing or by a straight forward sweeps followed by a strong backward sweep.
CN208503105U discloses a blade structure of an axial flow fan, comprising a hub and a plurality of blades with the same shape distributed around the hub. The utility model is characterized in that: the plurality of blades are all blades with LS airfoil characteristics. The said model has a complex arrangement where each of the blades includes five characteristic sections, and the characteristic section mounting angle of each feature section is a first characteristic section 27.74°, a second characteristic section 25.61°, a third characteristic section 21.61°, and a fourth characteristic section 20.70° and five characteristic section 20.33° with the center of gravity of the fan blade located in a circumferential plane perpendicular to the axis of the hub axis.
JP2012041833A discloses the fan includes a hub that rotates about a center axis, and a plurality of propeller blades that are fixed to an outer circumference surface of the hub with a gap there between in the circumferential direction and intake air from an intake side on an end side of the center axis direction and discharge the air to a discharge side on the other end side of the center axis direction by rotating about the center axis together with the hub.
US4358245A discloses a low noise, axial flow fan particularly suited for use in a turbulent air flow such as the flow exiting an automobile radiator has a band that is secured to the outer ends of the fan blades. The blades are highly forwardly skewed with an increasing blade angle as a function of blade radius over at least the outer portions of the blade where each blade is secured to the band along its full width. Further, in the preferred form, the band has a cross-sectional shape that acts as a nozzle to accelerate the airflow through the fan, each blade has a cambered, airfoil cross-section, and the entire fan is formed of an injection molded plastic as a single, integral structure.
CN210118280U discloses a fan blade for engine cooling, which comprises a wind guard ring, a blade and a hub; the blades have nine unequally distributed blades. The said arrangement is complex in its arrangement where the nine blades are arranged at unequal distances along the rotation circle to avoid the superposition of energy generated by the uniform arrangement reduces the unconventional order noise and optimizes the sound comfort.
EP0583091A2 a fan comprises a hub rotatable about a central axis and a plurality of blades each having a root region secured to the hub and extending radially outwardly to a tip region. The outer band 8 of the fan adds structural strength to the fan by supporting the blades at their tip and also serves to hold air on the working surface of the blades. The outer band is of uniform thickness but has a front most section which is curved to form a funneling effect.
The prior arts disclosed herein above that are directed towards noise reduction are complex in nature having non-uniform or uniform distribution of blades. None of the prior art references or the cooling fans conventionally available has been able to solve the problem of reduction of aero dynamic fan noise by minimizing turbulence effectively. Thus, there is a need in the art for replacement of the conventional designed cooling fan with new ring fan design that can be used for tractors with significant noise reduction.
Accordingly there is a need to provide an improved fan and a fan module comprising said fan, in particular a cooling fan module for an agricultural vehicle, particularly Tractor.
OBJECTIVES OF THE INVENTION
The main objective of the present invention is to provide a fan with a ring on its periphery for cooling system on Agricultural tractor
Another objective of the present invention is reduction of aero dynamic fan noise by minimizing turbulence along with uniform air flow and improved heat dissipation
SUMMARY OF THE INVENTION
Accordingly it is the primary aspect of the present invention to provide a ringed cooling fan (5) for a vehicle engine with reduced noise and improved heat dissipation, comprising:
a circular hub portion (2);
a plurality of fan blades (8);
a circumferential ring (10) positioned on the periphery of the said fan blades;
characterized in that the fan blades (8) are equidistantly placed, have a leading edge (09) and trailing edge (20), wherein the trailing edge is in contact with the hub (2), the blade has a convex surface (11) and a concave surface (12), the fan is configured to rotate in clockwise direction wherein the fan blades are sweep forward curved blades, and on rotation of the fan the convex portion (11) of the said fan blade in the upstream of the airflow and a concave portion (13) in the downstream of the air flow, the and
wherein the eddies at the edges of blades makes air flow uniform resulting in reduced noise and improved heat dissipation, and the ring (10) around the aerofoil, the air vortices formed by flow separation around the fan periphery are being broken upon contact with the ring (10).

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the said cooling fan (5) has at least 7 fan blades (8).

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the said cooling fan (5) has a diameter of 390-400mm

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the said fan hub (2) has a diameter of fan (5) is 394mm and diameter of hub (2) is 118nm.

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the camber angle of the aerofoil (30) is in the range of 3-18 degrees.

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the direction of the airflow is from the convex to the concave portion.

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the thickness ratio t/c is in the range of 3-7.

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein stagger angle is in the range of 45-62 degrees.

It is another aspect of the present invention to provide a ringed cooling fan for vehicle engine of tractors, wherein the pressure drop across the inlet/outlet of the fan draws fresh air thereby increasing the airflow.

BRIEF DESCRIPTION OF DRAWINGS
Figure 1(a) depicts the front view of the ringed cooling fan indicating the direction of air flow
Fig1 (b) depicts a sectional view of the ringed cooling fan
Fig 2 is a representation of the prior art
Fig 3 is an illustration for the camber angle measurement
Fig 4 is an illustration for the calculation of thickness ratio
Fig 5 is an illustration of the Stacking Point co-ordinates
Fig 6 is representation of co-ordinates of stacking points for Curve 1
Fig 7 is representation of co-ordinates of stacking points for Curve 2
Fig 8 is representation of co-ordinates of stacking points for Curve 3
Fig 9 is representation of co-ordinates of stacking points for Curve 4
Fig 10 is representation of co-ordinates of stacking points for Curve 5
Fig 11 is representation of co-ordinates of stacking points for Curve 6
Fig 12 is representation of co-ordinates of stacking points for Curve 7
Fig 13 is a representation of fan noise test results based on the present invention
Fig 14 is the representation of the cooling trail results based on the present invention

DETAILED DESCRIPTION OF THE INVENTION
The present invention as embodied by an “A ringed cooling fan for vehicle engine of tractors” succinctly fulfills the above-mentioned need[s] in the art. The present invention has objective[s] arising as a result of the above-mentioned need[s], said objective[s] having been enumerated hereinabove.
The following description is directed to a ringed cooling fan for vehicle engine of tractors as much as the objective(s) of the present invention are enumerated, it will be obvious to a person skilled in the art that, the enumerated objective(s) are not exhaustive of the present invention in its entirety, and are enclosed solely for the purpose of illustration. Further, the present invention encloses within its scope and purview, any structural alternative(s) and/or any functional equivalent(s) even though, such structural alternative(s) and/or any functional equivalent(s) are not mentioned explicitly herein or elsewhere, in the present disclosure. The present invention therefore encompasses also, any improvisation[s]/modification[s] applied to the structural alternative[s]/functional alternative[s] within its scope and purview. The present invention may be embodied in other specific form[s] without departing from the essential attributes thereof.
Furthermore, the terms and phrases used herein are not intended to be limiting, but rather are to provide an understandable description. Throughout this specification, the use of the word "comprise" and variations such as "comprises" and "comprising" may imply the inclusion of an element or elements not specifically recited.
Embodiments of the present invention discloses an axial fan (5) fixed to a motor shaft, and the motor (not shown in FIG. 1) is located inside a fan hub (2). The fan (5) can rotate around a rotation axis (6) by means of the motor shaft rotating inside the motor. The center (7) of the fan (5) and the rotation axis 6 of the fan (5) are indicated in FIG. 1. The present invention relates to a ring fan wherein the blades are forwardly skewed. The blade centerline curves in the direction of rotation of the fan assembly as the blade extends from the center of the hub to the ring in the circumference.
The fan (5), in particular an axial fan, comprises a plurality of fan blades (8). The fan blades can be of any finite number, for exemplary purpose only the no of blades indicated in figure 1 is 7. The blades as shown in FIG. 1 are slightly expanded at the rear. The fan blades (8) are attached at their lower end or rear end (20) to the fan hub (2) and are further connected to one another at their upper end or tip (9) via an outer fan ring (10). The fan (5) as shown in FIG. 1a, 1b is fixed to a motor shaft, and the motor (not shown in FIG. 1) is located inside a fan hub (2). The center (7) and the rotation axis (6) of the fan (5) are indicated in FIG. 1.
The fan blades (8) of the inventive fan (5) are specially designed as sweep forward curved blades. With reference to the accompanying drawings, the fan (5) rotates about an axis (6) and comprises a central hub (2) mounting a plurality of blades (8) curved in the plane of rotation XY of the fan (5). The blades (8) have a root or base (20) and a forward end (9) and are delimited by a convex edge (11) and a concave edge (13). The convex part (11) is the upstream or front end of the air flow and the concave part is the downstream of the airflow. The fan is running in clockwise direction from the front, so the convex part or edge (11) is the portion where the air will first hit.
In an embodiment of the present invention the fan diameter of is 390 mm to 400 mm. In the embodiment of the present invention the tapered air foil along with the ring (10) generates less turbulence there by lesser noise generation while ensuring maximum airflow efficiency for the cooling. The less turbulence also helps in achieving uniform heat dissipation of engines through natural evaporative cooling process. The air cutting angle drives the pressure drop across the inlet/outlet of the fan which draws fresh air accordingly. According to the blade geometries of the ring fan, the airflow can be increased drastically without changing the working rpm or the size of fan.
Since satisfactory results in terms of efficiency, noise level and head have been obtained by rotating the fan made according to the present invention, the ring fan provided efficiency mainly by its construction which is described in detail. The fan comprises for exemplary purposes only, 7 blades, each having a convex edge 11, and the concave edge (13) of the blade. In other words, the fan (1) may rotate in such a way that the air to be moved meets first with the convex edge (11) and then the concave edge (13). In fans the cross section of the blade is airfoil. Figure 3 illustrates an airfoil (30) of blade (8) having a leading edge (50), a trailing edge (32), and. The chord of airfoil 30 is the straight line (represented by the dimension "C") extending directly across the airfoil from leading edge (50) to trailing edge (52). The camber is the arching curve (represented by the dimension "b") extending along the center or mean line 40 of airfoil 30 from leading edge (50) to trailing edge (52). Camber is measured from a line extending between the leading and trailing edges of the airfoil (i.e., the chord length) and mean line (40) of airfoil (30). Maximum camber, Dmax, is the perpendicular distance from the chord line, C, to the point of maximum curvature on the airfoil mean line (40). A high camber provides high lift and, up to a limit, fan pumping is proportional to maximum airfoil camber.
As shown in FIG. 1b, when airfoil (30) contacts a stream of air (18), the air stream engages leading edge (9) and separates into streams (1-7 of figure 1b). Stream (42) passes along surface (36) while stream (44) passes along surface (38). As is well known, stream (42) travels a greater distance than stream (44), at a higher velocity, with the result that air adjacent to surface (36) is at a lower pressure than air adjacent to surface (38). Consequently, surface (36) is called the "suction side" of airfoil (30) and surface (38) is called the "pressure side" of airfoil (30). The pressure differential creates lift.
The present invention provides a ringed cooling fan (5) for vehicle engine of tractors with reduced noise and improved heat dissipation comprising: a circular hub portion (2) comprising a plurality of sweep forward curved fan blades (8) radially positioned from the said circular hub portion (2),a circumferential ring (10) positioned on the periphery of the said fan blades (8), wherein the said blades are equidistantly placed between each other, wherein the eddies at the edges of blades makes air flow uniform resulting in reduced noise and improved heat dissipation. The circumferential ring (10) provides for breaking of the air vortices at the leading edge (9) formed due to flow separation around the fan periphery, are broken when they come in contact with this ring (10).

The fan diameter of is preferably 390 mm to 400 mm. The tapered air foil along with the ring generates less turbulence there by lesser noise generation while ensuring maximum airflow efficiency for the cooling. Further, with the existence of ring around the aerofoil, the air vortices which form due to flow separation around the fan periphery, are broken when they come in contact with this ring. Hence there is no energy propagated outside. The less turbulence also helps in achieving uniform heat dissipation of engines through natural evaporative cooling process. The air cutting angle drives the pressure drop across the inlet/outlet of the fan which draws fresh air accordingly. According to the blade geometries of the ring fan, the airflow can be increased drastically without changing the working rpm or the size of fan. The flow separation/reversal also needs to be controlled along with the flow magnitude where the lips/rings/shrouds on the whole contributes to the said system.

BLADE DESIGN
Impact of blade design on turbulence - The air cutting angle basically drives the pressure drop across the inlet/outlet of the fan which draws fresh air accordingly. By optimizing the blade geometries, the airflow can be increased drastically without changing the working rpm or the size of fan. The flow separation/reversal also needs to be controlled along with the flow magnitude where the lips/rings/shrouds contribute as a system which is the basic idea of this invention. The chord of thicker air foil is the straight line (represented by the dimension "c") extending directly across the air foil from leading edge 50 to trailing edge 52. The camber is the arching curve (represented by the dimension "a") extending along the center or mean line (40) of thicker airfoil (30) from leading edge (32) to trailing edge (34). Camber is measured from a line extending between the leading and trailing edges of the airfoil (i.e., the chord length) and mean line (40) of the thicker airfoil.

Calculation of Camber Angle (CA):-
Tangent circles to the upper & Lower aerofoil (30) Curves created in Catia V5,created camber line (C) passing through trailing end (20) & Center points of circles upto the leading end (50). The present invention provides the advantages of reduction in airborne noise and better cooling performance are attributed to the air foil design at various cross sections. For exemplary purpose only the blade cross sections across 7 different positions as depicted in Figure 1(b) is provided. The different cross sections are labelled as position 1, 2, 3, 4, 5, 6 7 in figure 1(b). The critical design parameters of the ring fan (5) and the blade (8) design lies in Fig 1(b) the various radii cut from centre has been provided in the table 1, as mentioned below which has significant influence on the various parameters. Further, the different sections of the air foil with varying radii has a significant impact in the air flow.

Table 1: Cross section of the Blade and dimension.
Radius of Section
Section 1 R1 = 59mm
Section 2 R2 = 82mm
Section 3 R3 = 105 mm
Section 4 R4 = 128mm
Section 5 R5 = 151 mm
Section 6 R6 = 174 mm
Section 7 R7 = 194.5 mm

Summary of profile parameters and stagger angle:
The air foil with the 7 different sections provide different camber angle (Fig. 3 and Table 1) measurements where with the variation in radii observed to have a significant effect on the camber angle. Apart from that based on the below mentioned parameters the system generates a pressure drop resulting in a different air flow.

As is shown in FIGS. 3 and 4, C, the chord length, is the straight-line distance between the beginning and end of a circular arc camber line, and is measured at R, the radial distance from the axis of rotation is the stagger angle of a blade section, that is, the angle in degrees between the axis of rotation and the chord line. Ɵ the camber angle, that is, the angle in degrees of the leading edge tangent line and the trailing edge tangent line of a blade section at the radial distance. LAMBDA is the skew angle of a blade chord section in degrees, measured with respect to a radius through the center of the fan at a blade hub root at the radial distance R.

Table 2: Airfoil details of the blade.
R1 R2 R3 R4 R5 R6 R7
Radius in mm 59 82 105 128 151 174 194.5
Camber  17.29 16.283 15.938 17.95 12.03 8.22 3.65
Thickness ratio t/c 6.56 5.88 5.4 5.11 3.36 5 4.71
 Stagger 47.4° 48.2° 50.4° 56.3° 62° 58.9° 48.3°
Thickness ratio t(max)/c 6.775 6.1 5.7 5.36 4.87 5.27 6.02

Calculation of Thickness Ratio:-
1. Created a chord line & measure as shown.
2. Created a maximum diameter (Dmax is the diameter) Circle which is tangent to Upper & Lower aerofoil curves.
3.By using formula , T(max)/c. i,e, Maximum thickness / chord length, we have calculate the thickness ratio (Fig 4)

Measurement of the Stacking Point co-ordinates:-
Referring to fig 4. D Max represent the diameter of the circle which is tangent to upper and lower aerofoils, and is the maximum diameter across the aerofoil of the blade section. Further, chord line is indicated as the Line connecting Leading and trailing edges of aerofoil and is also represented as “C”.

Further, created a surface by using aerofoil curves & created C.G. Point & measure if from (0,0) Co-ordinate (Fig 5). Accordingly, the stacking points traces the airfoil surface with the said co-ordinated system. The stacking points are different points having specific values for different cross sections of the blade or the different aerofoils of different dimensions represented by Curve 1, 2, 3, 4, 5, 6 and 7 in figures 6-12 of the present invention.
Examples:
Referring to the figures 4-13 the different sections ranging from 1-7 with the varying radii and the corresponding stacking points has been plotted. Accordingly the curves 1-7 represent all co-ordinate points to arrive at the fan design of the present invention. The coordinates in the X-Y axis as represented in various curves are characteristic to the aerofoil of the cross sections of the blade.
Curve 1 (Figure 6)
Example 1: Dimensions of the Ring Fan according to a preferred embodiment of the present invention.
Table 3:
SECTION 1 Ranges
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

Table 4:
CO-ORDINATE OF STACKING POINTS 27.326 1.715

Curve 2: (Figure 7)
Table 5:
SECTION 2 Range
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

CO-ORDINATE OF STACKING POINTS 41 2.336

Curve 3 (Figure 8)
Table 6:
SECTION 3
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

CO-ORDINATE OF STACKING POINTS 44.639 2.434

Curve 4 (Figure 9)
Table 7:
SECTION 4
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES= 7

CO-ORDINATE OF STACKING POINTS 44.243 2.798

Curve 5 (Figure 10) Table 8:
SECTION 5 Ranges
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

CO-ORDINATE OF STACKING POINTS 48.239 1.281

Curve 6 (Figure 11)
Table 9:
SECTION 6
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

CO-ORDINATE OF STACKING POINTS 47.226 -1.491

Curve 7 (Figure 12)
Table 10:
SECTION 7
FAN DIAMETER = 394mm
HUB DIAMETER = 118mm
NUMBER OF BLADES = 7

CO-ORDINATE OF STACKING POINTS 43.628 -0.055

Reduction In Airborne Noise (Table 11)
Referring to the Fig.13, with respect to reduction in airborne noise, it is observed that
noise spectrum measurement at 3500 rpm is significantly low at tonal frequencies. Test has been carried out in anechoic chamber at component level.
Table 11
Fan 1st Blade Pass Frequency 2nd Blade Pass Frequency
Existing 411 64 822 72.7
Ring 402 60.5 804 61.2

Further, Tractor DPNL (Driver Perceived Noise Level) Noise where the absolute reduction on the DPNL noise levels were measured on 2 different tractor models with the help of proto samples and listed on the Table 12 below.
Table 12.
S.No. Tractor Engine Speed
(RPM) Fan Speed
(RPM) Fan pulley Ratio
DPNL dB (A)
Existing Ring
1 Model-1 2150 2623 1.22 88 87
2 Model-2 2250 3285 1.46 91 89.4

Better Cooling Performance
Referring to Fig.14 the result of the cooling test trials performed on tractor level with the existing and the present ring fan is calculated. The Power, Torque & SFC of ring fan are very much equivalent and Cooling performance i.e., Ambient clearance for both water and oil is higher by 2°C in comparison with the existing fan (Minimum ambient clearance for water and oil is 46°C).
Advantages of the present invention are:
1. Driver Ear’s noise reduction.
2. Improved air flow (or) cooling performance.
3. Reduction in power consumption
It will be apparent to a person skilled in the art that the above description is for illustrative purposes only and should not be considered as limiting. Various modifications, additions, alterations, and improvements without deviating from the spirit and the scope of the invention may be made by a person skilled in the art.